Modded Mustang Forums banner
1 - 7 of 7 Posts

Rebel Of The Sacred Heart
2,338 Posts
Discussion Starter · #1 · (Edited)
Well I thought some of you might like to read about a little paint theory. So i figured I would start a thread and type some and ill add more to it when i get time.
Also if there is anything specific you would like to read about, just let me know.

You can break your paint jobs down to three catagories: undercoat, midcoat, and topcoat

undercoat: etching primer, primer surfacer, epoxy primer, sealer, pretty much any primer or adhesion promoter. Your undercoat is what goes ontop of
bare metal or over the properly prepped previous paint, bodywork,etc... and it gives you a uniform coat that is a uniform color to apply your color ontop of.

midcoat: base coat, pearl coat, kandy coat, metal flake coat,etc... Your midcoat is going to be what ever goes ontop of your primer and under your clearcoat

Topcoat: The topcoat is the final coating in your paintjob, the clearcoat

So a little about the different types of undercoats and what some advantages and disadvantages there are associated with them.

Etching primer: A primer that is desinged to go over bare metal. It has a high acid content and uses it to etch the metal and conditions it for increased adhesion, and will help prevent corrosion in the future.
It is recommended to use an etching primer on galvanized and stainless steel to get the maximum adhesion for the rest of your coats. However you dont want to spray your basecoat directly ontop of etching primer.
You always want to spray a sealer or primer filler then sealer before moving on to your basecoat. And self-etching primer is not really a "sandable" primer.

Primer-surfacer: There are a few types of primer- surfacer availeble such as lacquer, enamel, and polyuerethane enamel. They all are a high-solids type paint, that is desinged to build up the surface, fill minor imperfections such as sand scratches or pinholes, to further refine and finish bodywork, and provide a sutible surface for sanding. However primer surfacer usually has to be sanded before proceeding, unless it is a wet-on-wet aplication. That is why if you dont need the filling properties of it, it is best to just use a sealer before the basecoat.

Primer-sealer: Sealers are what you use to prepare existing finishes, by increasing adhesion, making it one uniform color, isolating any problems on the old finish underneath the sealer. This primer can also be used in a wet-on-wet manner.

Most paint companies have tintable sealer lines, which helps create hiding and correct color in few coats of basecoat.

Epoxy primer: Epoxy primer is a very good primer with all around good characteristics. It has good adhesion over bare metal, existing finishes, has excelent corrosion resistance, it has great fill and build qualities, and can be sanded. However the cure time on epoxies are longer. But where time is not a factor epoxies are a great primer.

Adhesion promoter: Ashesion promoter is mainly used when you are painting plastic pieces, ie. door panels, chin spoilers, interior peices, mirrors, etc... When you are painting raw plastic(plastic that hasent been painted before) You dont want to sand it with an agressive(a low number) grit of sandpaper or you run the risk of having mold release, that soaked into the plastic during the molding process, leach to the surface through the deep scratches and cause adhesion problems. And since you sand the plastic with a higher grit, meaning there will be less profile(a term used to describe the "roughness" of a surface prior to painting) for the paint to "grab" onto, it is a good idea to use the adhesion promoter to ensure your primer sticks to the plastic. The way it works is when you are ready to spray your primer, first spray a medium coat of adhesion promoter over the entire peice, and while it is still tacky apply your primer. It basically softens the plastic a little making it easier for the primer to bond with it seeing as how there is not alot of profile for the primer to "bite" into.

Now for some midcoats.

Single stage paint: Think of single stage as basecoat and clear in one. It was the thing to use before urethane basecoat/clearcoat paint came out, and now it is still used but base/clear is preffered by most. It is cheaper than buying basecoat and clearcoat, but it doesnt have the
uv protection that a basecoat/clearcot job will have. It may also be harder for some people to spray espicially in metallics because it is wet coats all the time, as opposed to medium coats of color when using a basecoat. Since you are spraying wet coats of your color it will be easier to get a run, and a run in mettalic single-stage means a repaint, but with a basecoat/clearcoat the base is medium coats with wet coats of clear, and any runs in your clear can be sanded and buffed out. If you get a run in a solid color single stage,
then you can sand and buff it out. Just not on the metallic, because the orientation of the metallics in the paint will be messed up during sanding and it will be extremely noticable. You can also put a clear coat over single stage, but if your going to clear your single stage, you might as well use a urethane basecoat.

Basecoat: This is what gives your paintjob the color.It can be solid color, pearl color(a solid with pearl mixed in it), or a metalic(solid color with metalics mixed in it) You basicly have two types of basecoats, a urethane, and a lacquer.

Since lacquer dries by solvent evaporation, it does not require a catalyst. It will also "re-wet" if sovlent is introduced to the dried paint film. A good example of this is sometimes when laquer base coats are applied over laquer primer sand scratch swelling can occur. Thats where the solvents in the color re-wets the primer that you have sanded to
get it ready for color and the sand scratches swell up and become visible. But Lacquer paint is far cheaper than ureathanes.

Then you have your urethane color coat. This is by far the easiest way to apply color and also the most forgiving way, since you are applying medium coats so there is almost no chance of runs in the color. Urethanes dry by solvent evaporation and must be topcoated with a
clearcoat to protect the color and make it shine, because basecoat dries to a dull finish. It also dries to the touch relitivly fast, so it is ideal for graphics where multiple colors or tape is used. Most basecoats are desinged to achive hiding and correct color in 2-3 coats and are
clean up alot easier than lacquers and can be sprayed at lower pressures than laqcuer, therefore decreasing the overspray and increasing the amount of material that actually goes on the car.

Pearlcoat: A pearl coat is different than a basecoat that has pearl mixed in it. It is applied over your basecoat and that gives your paint job another "coat" which is what a tri-coat paintjob is reffering to. Thats basecoat-pearlcoat-clearcoat. It is actually a clear basecoat( pretty much just a binder with no pigments in it) with a pearl mixed in it, so that when srayed ontop of your basecoat there is a layer of pearl over your color. This is what gives you your color change effects , and the more coats applied the darker and more pronounced the pearl becomes. So it is advised to do a let-down panel when reparing a car that has a tri-coat paint job. Thats where you paint a scrap panel with your basecoat and then spray one coat of pearl on the entire panel. Then mask off a small section at the top(like a 2 or 3 inch piece of masking tape) and then put another layer of pearl over the panel. Then mask off another section and put another coat on it, and repeat that until you have a color that you know is darker than you need. Then clear it and let it dry. Then you can take your let-down panel and compare it to your paintjob so you know exactly
how many layers of pearl needed to match your paintjob. Blending a tri-coat paint job is almost an art form, and take spractice to be able to get it right on your first try. Because not only are you haveing to blend your colorcoat onto the existing color, but you have to blend the pearl into it as well.
And remember the more coats of pearl, the more pronounced it is. So its a fine line between having enough pearl on your repair area and blending it onto the existing finish with out adding so much pearl in your blend area that the original finish now has too much pearl on it. But it is a very satisfying feeling
when you can blend tri-coats perfectly.

Metallic coat: Again its different than a color with metallics in it. It is sprayed over your colorcoat. The easiest way to explain this is think of a bass boat, and picture the enourmous piesces of metal flake you see ontop of the color, that is a metallic coat. It comes in many different colors and sizes
ranging from bass boat flake, to tiny metal flakes. With the larger flakes you will need a large needle and fluid nozzle to let the chunks of metal flow through the paint gun. It is also benificial to have a gun with a self agitator in it. Its a little mixer that is in some suction feed guns that keeps the metal flakes aggitated and thoroghly mixed in the paint, instead of spurts of little and lots of metal flakes. Also the larger the flakes the more coats of clear is neede to completly cover them and give you enough to sand and buff.

Kandy coat: Think of kandy as a clearcoat with color added to it, but doesnt affect the transperancy of the clear. You could compare it to what cough syrup looks like in a way. It is always applied over another basecoat. When looking a a kandy paint job you are looking throught the color of the kandy to see the your color/or basecoat. So it dramaticlly affects the color of your basecoat. It is also the hardest thing to spray, and you have to be in complete control of your gun mechanics, a perfect spraying gun you familiar with, and have
excellent painting discipline. It is extremely easy to get light and dark splotches and tiger stripes with kandy, because the more coats of kandy, the darker it gets. A true kandy(not just a translucent color) will turn almost completely black when enough coats are applied, wich makes it ideal for airbrushing because the shading possibilities are endless. In order to get a perfect deep as glass kandy job you have to apply it with perfect overlap, because anyvariation while moving down the panel will result in light/dark areas so you have to be perfect in your overlap, and a dead on consistant spraying path on the car. The only way you can get a truely perfect match on an entire car with a kandy, is to paint it with all the panels on the car and paint the entire sides as one panel. I mean you couldnt paint the car with the hood, fender, doors, and decklid off so you dont have to spray the jambs beforehand and expect a consistant film on all the panels. If you do end up with light or dark splotches or lines or any bad imperfetions, you cant just fix them with more kandy. Because remember more coats of kandy just means it gets darker, not it hides mistakes. If you have dark light areas anywhere on the vehicle and you want it right, you have to completley start over with the basecoat. Witch is why a
good looking kandy paint job is very expensive. Because your either paying for someone that can do it right and get it done the first time, or paying the average painter that may have to start completley over because he a couple inches off on a few passes on his last coat of kandy. Now material price just doubled, and he still may not get it right the second time, pretty much the reason a good kandy job is so expensive is your paying for the knowledge and expertise of the painter. But there is absoulutly no replacement for the beauty of a perfect kandy job, that looks deep enouogh you can just reach right into the paintjob.


The topcoat will be your clearcoat on a base/clear job, or when you are doing a single stage paint job since there is no clearcoat, your color is considerd your topcoat instead of being a midcoat. The clear is what gives your paint job its protection, whether it be uv protection, chemical resistance, or even protection from the weather, and its also what makes your paint shine and have that wet look.

Basicly you have two types of clear, lacquer and uerethane enamel. Painters dont really use lacquer anymore, because the urethane is a FAR superior product. Urethane has much better protection qualites and is a better uv shield, so im not going to get into the lacquer clear and just focus on the urethane since i would never recomend it to someone to use, especially if it is someone learning to paint. The urethane is just that much better and is alot more forgiving on the painter. You also want to use a high solids clear(almost all automotive clear is high solids now) because it will take less material to get your film build up you need. I will get deeper into urethane clearcoats when i get to the actual spraying part of the thread.

Rebel Of The Sacred Heart
2,338 Posts
Discussion Starter · #9 ·
Thanks for all the nice feedback sofar, and there will be A TON more info in here when im done talking about everything i want to mention.

Hey you should add Adhesion in the undercoat. If your painting something like wheels you would spray Adhesion instead of primer.. Just a thought.

nice write up travis_afx

Spray Adhesion instead of primer? Not familiar with that one. Pretty much use epoxy primer for most everything.
Yeah ill add adhesion promoter to the list, but its not gonna be how you are thinking 98. Im not really sure why you would use straight adhesion promoter when painting wheels instead of primer. That just doesnt make any sense to not use primer. The only time you really need adhesion promoter is when painting plastics, because you really shouldnt sand them reall aggresivly or you can cause release agents that have leached into the plastic during the mold process to come back to the surface and cause adhesion problems, and even then you would still prime it after the adhesion promoter and before the midcoats. If your painting wheels that are bare metal then an etching primer or an epoxy like gtr07 mentioned is needed, and if they are powdercoated then either sealer primer or again a nice epoxy primer.

ok, so we got a detailed write up on paints.... how bout a write up on how to make a cheapish temporary paint booth in out back yards? :) If Im gonna try to spray a car, I dont think I should do it in my driveway under the black walhut trees.... :)

I gotcha covered bro, ill add the paint booth in here tonight. Its a very easy booth to build and i have painted in several like it before with great results.

Again i really like the feedback from you guys, the more suggestions of what exactly you guys want to read about, the sooner i will get something written about it. With no suggestions ill just continue to write about stuff till i run out of things to talk about.

Rebel Of The Sacred Heart
2,338 Posts
Discussion Starter · #12 ·
Surface prep

There are alot of factors that will go into deciding the right way to prepare your surface for paint. Will it be a simple scuff and repaint, is there bodywork, are there things that need to be removed from the panel(moldings, door handles, mirrors, emblems,etc..)is it bare metal, is it raw plastic, is the paint your going over in good condition or is it delaminating, etc....

So ill try and do this in an orginized manner, but if i get confusing just ask and ill explain it better.

So preperation always begins with giving the area to be painted, whether its a whole car or just one part of a car, getting washed with good old fashined soap and water. After you have it washed and dried off you will begin to remove things that shouldnt be on it when painting,such as moldings, door handles, emblems, etc.... You must remove items like that so you can get a continuos paint film. When trim, moldings, emblems, etc... are not removed you are asking for trouble and will create an open edge around whatever you left on and just masked off.
The open edge often leads peeling of the paint film down the road, and is a big red flag that the car has been repainted. Things left on are also great places for moisture, dirt, and other contaminates which can come out later on in the painting process. So it would be in your best interst to just go ahead and remove anything like that in the begining and save yourself some headaches. One thing that cant easilly be removed that will cause a open edge is the reveal molding(the rubber gasket type thing around the outside of the glass) around the winshield and back glass. It is either made onto the glass or glued in with the winshield urethane holding the glass to the car. So unless you can easily remove and install those peices of glass, you will have to do something with the problem of the moulding touching the paint surface.
I DO NOT recomend anyone removing and installing the front or back glass that does not know exactly what they are doing, two reasons for this: 1. it is VERY easy to break the glass while cutting it out if you dont know how to do it properly, and 2. the windshield and the back glass are major sturctural componets in unibody cars and if not installed properly can result in major damage, injury, even death in the event of a wreck. The way to get around not removing the glass is to "lift" the rubber off the surface while painting and then laying it back down after the paint has cured. There is a thing called lifting tape, that is desinged to go under the moulding and it lifts up the rubber. Ive also used rope, speaker cable, and other various things. You can use pretty much anything you want, so long as its something clean and it lifts the rubber high enough up that the clear edge is completely under the moulding after you remove the lifter and let the moulding lay back down on the paint. Another good reason to remove mouldings and such is that while sanding one little accidental bump into it with your sander and it could be ruined. Also you need to be sure to remove any adhesive left on the paint after removing the item. This can be accmplished with some 3m adhesive remover and a little elbow grease. Alot of people swear by goo-gone, but i hve never used it so i cant really comment on it, but ive never heard of anyone having a problem with it.

So now that you washed your vehicle and removed anything you need to, its time to wipe the area to be painted with a wax and grease remover. You will need two seperate rags for this, one wet that you use to wipe the w&g remover onto the panel, and a dry one to wipe off the w&g remover. It will allow any dirt or contaminates to be "floated" above the surface in the sovlent, and that in turn lets you wipe off all remaining contaminates and the solvent with your dry rag. Work in small areas so it doesnt dry before you get to wipe it off. If it does dry before you wipe it off, you have to do it again without letting it dry. You never want to let freshly wiped on wax and grease remover just evaporate without wiping it with your clean dry rag first. Also change rags often if you have alot to wipe down, because if you are wiping on or off with a dirty rag, your are just moving the contaminates around and not actually removing them from the panel. Parts such as bumper covers may need to be wiped down with an additional step using an anti static solvent. If you skip that part the bumper will atract dust and dirt like a magnet ruining your paint job. If it is a raw bumper it is a good idea to wipe it down with a water based cleaner, beacuse it might still have mold realease on the surface and it is water soluble, meaning your normal solvent based wax and grease remover will not remove it, causing adhesion problems later.

........more surface prep to come later tonight.........

Rebel Of The Sacred Heart
2,338 Posts
Discussion Starter · #17 · (Edited)
Now a little about different kinds of sandpaper and other things used to scuff or sand the surface to get it ready for paint. There are basicly three types of sanding media used in refinishing: wet or dry sandpaper, dry sandpaper, and scotchbrite(red, grey, and white). Wet or dry paper is used in wet sanding, it has a special backing paper that will not be affected by water and will be come more pliable when wet. Dry paper is used for dry sanding, and the various grades of scotchbrite is used when sandpaper is not needed to achieve the proper "roughness" for the paintjob or it just wouldnt make sincde to use sandpaper, like the underside of a hood for example.

Here are the common grits you would use and what they are generally used for(disclamer:different painters prefer different grits sometimes and these are my preference):

36 grit: A VERY coarse sanding disc, used when doing metal work. I would not recomend using this on newer cars, as the metal is so thin as compared to say the 60s and 70s
80 grit: Used when metal working, prepping metal for body filler, intial sanding of body filler(you should get the shape of your filler finished with 80 and the subsequent grits are used mainly to remove the previous grit's scratches)
120 grit: Used on your body filler to remove the 80grit scratches
180 grit: Final sanding of body filler removing the 120 grit scratches
320 grit: Feathering any paint edges around the repair area with a DA sander, sanding the paint around the repair area that will be primed with primer-surfacer(you actually want to go a little further than where you will be stoping the primer)
400 grit: Dry sanding primer surfacer
600 grit: Sanding any paint that will have primer sealer over it, wetsanding primer surfacer, blocking any small dings out that are shallow enough to be taken out with only sanding the paint, no surfacer.
1000 grit: Wet sanding any existing paint finish that will have basecoat sprayed directly on it(no sealer)
1500 grit: Wet sanding clearcoat
2000 grit: Wet sanding clearcoat, and removing 1500 grit scratches if it was used
2500 grit: Wet sanding clearcoat, sanding out dirt nibs, removing 2000 grit scratches if it was used
3000 grit: Final wet sanding clearcoat by removing 2500 grit scratches

Red scotchbrite: Scuffing paint that will be primed
Grey scotchbrite: Scuffing paint that will be based(no sealer)
White scotchbrite: Scuffing paint where a clearcoat blend is preformed

When you are wetsanding it is best to let your paper soak a few minutes before using it.

When wetsanding clearcoat add a couple of drops of dishsoap to help lubricate the paper and make the sanding go faster.

There are sanders called jiterbugs, that are like a da sander but has a rectangle pad and dosent spin, it is very useful in block sanding larger primer surfacer areas.

There are pastes(3m's is called sand-ez) that you can use when scotchbriting something and it helsp speed up the scuffing process and make the sanding more uniform. Before this stugg came out, painters used comet with their scotch brite pads getting a similar effect.

Try to avoid making vertical and circular sand scratches, always try to sand horizontally(or what i like to call sanding with the panel). Like on a door sand with strokes that go from the back to the front, instead of strokes that go from the top to the bottom or circular strokes. Horizontal scratches are harder for the naked eye to pick up. The only tim you should deviate from this method is if you are sanding body filler or primer surfacer, and then you would use a crosshatch method. Meanig sand in one direction for a few strokes, and then sand in the oppisite direction for a few strokes making a sort of x pattern. But alway try and finish with your horizontal strokes. If vertical and circular strokes are sanded into the clearcoat getting it ready to buff, those scratches are harder to buff out than the horizontal strokes.

Scotchbrite pads are a type of expanded nylon material that is impregnated with an abrasive. The scratches(or profile) left by the pads are more random than sandpaper because of the "open" consturction of the pads.

Here are a few do's and dont's of sanding i have picked up.


Clean the area to be sanded with soap and water and then a wax and grease remover

Use a foam sanding pad when hand sanding to avoid sanding "finger grooves" into the finish

Tear or cut sanpaper sheets cleanly. A rough edge tends to gouge the surface.

Use a finer sandpaper when wetsanding as opposed to dry sanding because the wetsanding is more aggressive.

Use a guide coat when sanding to avoid over sanding and to help identify low spots.

Turn down the speed on your da sander near bodylines.


Use excessive pressure or speed when sanding to save time, because often times it will just mess it up and cause more work for you in the long run.

DO NOT i repeat DO NOT sand over body lines when block sanding. Take a body line on a door that is right in the middle for example. First block everything above the bodyline sanding down to, but not over, the bodyline. Then sand everything below the body line sanding up to, but not over, the bodyline. When you sand over a body line all you eill be doing is ruining the crisp like and causing more work for you. I like to take a piece of 3/4" masking tape and put it right on the bottom side of the line when im sanding above the line so i know exactly where to stop. And a piece right above the line when im sanding below the bodyline.

Rebel Of The Sacred Heart
2,338 Posts
Discussion Starter · #18 ·
how to make a cheap paintbooth

Materials needed:

3/4" pvc pipe and joints
Duct tape
Flourescent lights
An Exhaust fan

First start out by making the frame out of your pvc pipe, You can make the booth any size you want, but remmeber the bigger it is the more exhaust power you will need. to fit a whole vehicle in it i like to have at least a 2-3 feet on each side of the car so there is enough room for me to bend down. and around 3-4 feet in front and in back of the car.

After you have settled on the size and have assembled the frame without using the pvc cement, it is time to cover it with your plastic. I have found the best thing for me to use is "painters plastic"

it lets alot of ligth through and comes in 12' X 400' rolls,

So start by taping one edger of the plastic to one of the corner pipes, from the bottom all the way to the top. If thhe plastic is to tall dont worry about that. Start stretching the plastic all the way atound the pvc pipe. Keep the plastic tight but dont stretch it so much it rips, you want it just tight enough to get rid off all the slack. When you get back to the corner you stared at cut the plastic and tape that end onto the plastic about 12" around the starting corner.

Now you need to make a door. How wide it is will be determined by what you are moving in the booth. If it is parts that you can carry in by hand you can make a smaller door. If you are making it big enough to panit a car just cut about 12" in from each corner. No matter how wide it is, the principle behind how the door works is exactly the same. You will want to cut a flap in the wall. Cut the both sides from the bottom to the height you need to move the parts in. When you wrap the frame with the plastic, if you will leave about 12" excess on the bottom you can use sand bags lying on top of the excess to seal the bottom edge of the booth and hold the bottom of the door closed. You can seal the side of the door a coule ways you can tape the seams shut or you can affix some velcro to the deges and use that to hold the door closed. If you tape a poll to the bottom of the door it makes it easier to roll up when ou need to upen the door, it will make opening it by yourself alot easier.

Now that the booth is built and the door is in we need to get an eshaust fan going. You can use just about any fan. I have used everything from box fans, the fans on the tops of ac units, squirel cages, etc..... The main thing to remmeber is to get enough air movement for how big the booth is. if all you can come up with is low poweed fans you might need a couple of them. At the oppisite end of the booth from the door, you will need to cut out an opening for the suction end of the fan. You can either build a stand for it to raise it up or just have it sit on the ground. After the hole is made and the fan is in place you need to seal the plastic to the fan housing using the duct tape. Then tape a filter onto the opening so the overspray gets caught and not blown outside.

Now anytime you have an exhaust fan you need a return air opening. This opening will euqal out the pressure in side the booth so the whole thing doesnt collapse on its self. So cut a hole in the wall away from the fan(s). You will want to take the return air filters for home ac units and tape them in the opening with the duct tape. You may need multiple return air holes depending on how many cfms your exhaust fan moves.

Now the last part is the lights. I like the double tube flourescent lights personaly. The more lights you have the eaiser it will be to paint. There is a couple reasons for this. One, the more light the easier it will be to see in the booth, and two, the more light bulbs you have the easier it will be to find a "light bar" on the paint surface. That is a reflection of the actual bulb on the panel which allows you to see how wet you are putting the paint on easier. You can also keep track of your overlap easier when looking at a "light bar". I like to have vertical and horizontal lights set up, again so i have multiple "light bars" to choose from. You just want to set them up outside the booth facing in. I use stands for my lights.

Rebel Of The Sacred Heart
2,338 Posts
Discussion Starter · #23 ·
One of the most important things when painting is your gun control. To get the best possible results, you need to paint like a robot. Meaning you want to have absolute control over your gun, so you are spraying the same amount of paint over everything. Now the MOST important thing in painting is the surface prep, because ANY imperfections on the panel will be magnified when painted. But second to that is your gun mechanics. Thats what ill talk about this time.

First let me talk a little about the different sprayguns available. You can break down all sprayguns into two basic catagories: Conventional, or a high pressure gun, and HVLP, or a low pressure gun.

Conventional guns have been pretty much replaced by HVLP guns, because HVLP guns have such a better transfer efficiency, and that boils down to alot of paint being wasted by not making it onto the panel using a Conventional gun. So all im going to say about them is that they are yesterdays technology, and if your going to get spray, use a HVLP. Now im sure there will be some people say "I have a such and such convetional gun and i can spray paint great with it". That is not the fact im debating. I have used both and i can get great paint jobs from conventional guns, but i like to make my painting as easy and as cost effective as possible. The HVLP are just a better gun than the old conventional guns in all fronts.

Now for HVLP, or High Volume Low Pressure. They are called HVLP cause say you have 40psi of air coming into the gun, by the time it leaves the gun atomizing the paint, its down to like 10 or 15psi but still has the volume of air that the original 40 psi has. And the lower the psi leaving the gun, the less overspray you will produce. All true hvlp guns will have a 65% or better transfer efficiency(meaning 65% of the paint coming out of the gun makes it to the panel, and the rest is lost through overspray). There are even some HVLP guns when set up correctly that have 80-90% transfer efficiency. Having a gun with a high transfer efficiency equals less spray time and less cost involved in a paint job. MY preference on HVLP guns is Accuspray, but ill say i also love Iwata and Sata guns also. They are all three good brands and it boils down to personal preference. Just remember with a paint gun, the old saying that "you get what you pay for" is a good rule of thumb. Im not saying you cant get good looking paint jobs with a cheaper gun, but the expensive guns are expensive for a reason, its cause they are flat out a better gun and that makes it easier to paint.

Then you can further break those two categories into two more: gravity fed(paint cup on top) and siphon fed(paint cup on bottom). This will also come into a personal prefference thing, but ill say a gravity fed gun is easier to use, clean, and learn with.

I almost always paint with a gravity fed gun, but my favorite and best performing gun i have is a siphon fed. It is an Accuspray #10 Gun, It has the softest and evenest spray pattern i have ever seen, and amazing transfer efficiency. It is also in a sub-group of siphon fed guns, which is a pressurized siphon fed gun. Than means there is an extra air line that puts about 8psi of pressure inside the cup and that forces the paint up into the draw tube.

So now that the guns are kinda out of the way, lets talk about your gun control. A good rule of thumb to follow is the 8X8 rule. That is with your gun 8 inches away from the surface you have a 8 inch wide pattern. You can adjust the width of your pattern using the fan control knob on the gun. You Always want to stay at a ninety degree angle from the panel you are spraying. If your distance is inconsistent(i.e. the distance from the gun to the panel is not the same for every pass you make then you will have thickness variations in your paint film. Thats because the closer you are the thicker the paint will end up on the panel and the further away the thinner the paint film will be. Now you can get away with a little variation in your distance on solid colors, but on a metallic or pearl paint inconsistent distance will wreak havoc, leaving light and dark spots in your base coat.

Next lets talk about your overlap, or how much each pass overlaps the previous pass. Now normally for basecoats you want a 50-60% overlap. For clearcoats I like to use a 65-70% overlap. Again, you might like to have a different % of overlap due to personal preference. Another thing that you need to do is when you make your first pass, say with using a 50% overlap, spray "above" the panel where your only hitting your panel with 50% of your pattern, and on your last pass spray "below" the panel again and so you get your 50% overlap on all passes. If you dont do those two things your top and bottom pass will not have the same thickness as the rest of the panel. and that can come back to bite later, especially with metallics.

So if your spraying metallic basecoat do yourself a favor and use no less than 60% overlap. That will help you reduce tiger stripes in the basecoat. Tiger stripes are the light or dark lines you see in poorly painted paint jobs, and 9 out of 10 times they are cause by to small off overlap or an inconsistent overlap. If you do end up having tiger stripes, you can try and correct them by doing mist coats over the panel. A mist coat is where you widen up the spray pattern, increase the air pressure, and bring the paint gun far away from the panel and just "mist" the basecoat on the panel and that will sometimes hide the tiger stripes. Just be mindful that doing mist coats with mettalics has the potential to make the color lighter than it should be, because you are putting on a light coat and that wont allow the metallic to orientate corectly because there is not enough solvent to let the mettalic flow out right. That is why it is important to just use consistent overlap and not have tiger stripes to begin with. Dont be discouraged if the first time you paint a metallic it looks like crap, especially if you dont have excellent gun control. Bieng able to spray a perfect metallic paint job takes practice, concentration, excellent gun control, and being able to fix a tiger striped paint job is almost an art form. So sometimes it is more plausible for a painter to just start over then try and fix it by using spray tricks.

You also want to have consistent gun speed, or how fast you are moving while making a pass. If you are constantly slowing down and speeding up, it will effect how the paint flows out, especially metallics, which in turn will affect your paint thickness.

Just a little about your fluid tip sizes, and this is just my prefference, so im sure others like it different ways, but this is what i have found to work the best for me.
I like a 1.2-1.3 for base, 1.4 for my clear and sealer, and a 1.8 for primer surfacer. If you can only get one gun and not have a seperate gun for primer, base, sealer, and clearcoat I would recommend a 1.4 tip would be the one to get. Better to have a little bit to big of a tip with your base, than having to small of one and starving the gun when spraying the clear.

So all in all you want to act like a robot when painting, meaning you want everything you do while painting is exactly the same. The only way to really get complete gun control and get to where you are comfortable spraying any and everything is practice practice practice. I have sprayed hundreds of gallons of paint to get my gun control, but now i can say with all confidence there is not a coating i cant spray and make it look good. So when you first start out and its not going how you planned, you just have to keep trying. Noone is a painting master the first time they pick up a gun. Even after all the paint i sprayed, i can usually find something i can learn from on every paint job i do. When you stop learning new things, you are going to limit yourself on how good a job you do. Always try and take something new from every painting experience you have.

Rebel Of The Sacred Heart
2,338 Posts
Discussion Starter · #24 ·
And here is a little about spraying your basecoat and clearcoat, and how to know when its time to put your next coat on.

Every paint manufacturer will have a set amount of time to wait between coats, it will be something like [email protected] or something along those lines, and wherever you buy your paint should be able to give you a copy of the tech sheet for that product and it will have all that info on it. Just remember when looking at the tech sheet if it is a time at 70 degrees and its not 70 degrees where your painting you have to account for that.

Now with that said I'll tell you how i do it.

Your base coat should be put on as medium coats, meaning it shouldnt look "wet", just almost wet. I know that sounds confusing but you want medium coats of base because it is desinged to be applied in thin coats, unlike clearcoat that is sprayed on "wet" because it is desinged to be put on in thicker coats. After you put on a coat of base, using about a 50-60% overlap with each pass, and it has enough time to flash off(time to dry) the basecoat will have a dull look to it and is dry, completly dry to the touch. Making sure its fully dry is important because you will want to wipe down the entire surface with a tac rag before starting and between every coat of paint(clearcoat excluded, because its still wet when the next coat is applied).

So when your basecoat has a nice dull finish over the whole surface and is dry to the touch its ready to be tac raged off and another coat applied.

Now for the clear coat. Let me start by telling you to put a tac coat of clear on before you apply any wet coats. It will reduce your chances of getting a sag or run in your first coat of clear by giving the clearcoat something with a little profile to it to adhere to, instead of the smoth basecoat. What i mean by tac coat, is a light coat of clear over the entire car. And it truly is a light coat, you are just spraying enough clear on the surface to make it tacky. And then after you spray your tac coat, immediatly start with your first wet coat of clear, because it is such a light coat, by the time you spray one on the whole car it will be dry enough to start your first coat. Then after you have sprayed your wet coat, do the stringy test to see when its time to put the next coat on.

Stringy test: choose an area that is masked off near the painted surface, and press your finger on it. When the clear is still wet it will feel kinda like sticking your finger in some sryup, that is to wet and you need to wait longer. As it starts to dry, it will become stickier and stickier. To the point to where when you press your finger on it and pull it off there will be strings going between your finger and the cleared surface. How i tell when it is time to put the next coat on is when i can press my finger on it and there be many many strings between my finger and the car. Like for example when it first starts "stringing" there might only be two or three strings, but when it is dry enough to put the next coat on , there could be twenty or thirty strings. Do it in a few places around the car. I hope that makes sense, its kinda hard to explain.

With my clear coat on "normal jobs"(one where i am going to be matching the factory orange peel) i put a tac coat and two wet coats of clear. For a car that the owner wants a smooth as glass clearcoat, i do a tac coat and 3 wet coats, that way i know i have enough clear on there to sand it down smooth and still have enough clear thickness that it doesnt make the clearcoat fail down the road. On paint jobs with graphics(or racing stripes) in them i will do a tac coat and 4-5 wet coats of clear because it will take alot more sanding to level the paint down to where you cant feel the graphics edge anymore.

Now I like to have a little more overlap with my clearcoat passes, so i usually use a 70% overlap on my clear coat passes. Except for the tac coat, where i use like a 40-50% overlap, cause your not really trying for a really even coat, just a quick light coat to make it tacky.

The overlaps and process for spraying Kandies is kinda hard to explain, because you really shouldnt even attempt to spray an actual kandy job on a car unless you are absolutely positive you can have exact gun control for the entire job. One tiny little mistake on a kandie job and you have to start all over from scratch. There is no going back and fixing a mess up in a kandie job, its either you do it right the first time or you start over with the basecoat. That is why a good kandie job will cost you 5, 6, 7 thousand dollars and maybe more depending on what base and kandie is involved and the shape of the car being sprayed, because not only are you paying for the paint job you are paying for the skill of the painter that can do a perfect kandie job, and not just any painter can do that.
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.